This document summarizes research on the dynamic properties of a magnetic levitation system using high-temperature superconductors. Researchers measured the spring constant and damping constant of the system by analyzing its damped oscillatory behavior. They found that the spring constant decreased with increasing initial oscillation position, while the damping constant increased. They also proposed a new measurement method using repetitive control to evaluate properties as a function of oscillation velocity. This showed both spring and damping constants decreased with increasing input frequency. Analysis of hysteresis losses implied hysteresis significantly affects oscillation attenuation. In summary, the document examines the dynamic behavior of a superconductor-based magnetic levitation system through oscillation analysis and a new repetitive control method.
Higher-Order Squeezing of a Generic Quadratically-Coupled Optomechanical SystemIOSRJAP
Using short-time dynamics and analytical solution of Heisenberg equation of motion for the Hamiltonian of quadratically-coupled optomechanical system for different field modes, we have investigated the existence of higher-order single mode squeezing, sum squeezing and difference squeezing in absence of driving and dissipation. Depth of squeezing increases with order number for higher-order single mode squeezing. Squeezing factor exhibits a series of revival-collapse phenomena for single mode, which becomes more pronounced as order number increases. In case of sum squeezing amounts of squeezing is greater than single mode higher-order squeezing (n = 2). It is also greater than from difference squeezing for same set of interaction parameters. Sum squeezing is prominently better for extracting information regarding squeezing.
Control of vibration through an innovative isolation technique of a multistor...eSAT Journals
Abstract
The paper presents a simple and an innovative idea regarding vibration isolation technique of a multistory building using magnetic
field and is proposed to application in the field of civil engineering structures. This idea is fully based on hypothetical concept, but the
objective is to explore this idea or concept in to the entire community which may be a potential sector for the effective vibration
isolation system. The technique is described based on the magnetic properties of materials and a magnetic field characteristic which
depends on the amount of current flow, number of turns in coil, distance between electromagnet and the magnetic materials.
Therefore using magnetic field, the attraction induced between magnet and magnetic materials, a force could finally be developed on
the floor of building. This force would become effective until and unless the power is cutoff. Therefore this induced force is actually
acts as a live load on the structure which indirectly increases the weight and this has been described in this paper.
Keywords: - Isolation, vibration, frequency, magnetic field, performance based design, damping
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Higher-Order Squeezing of a Generic Quadratically-Coupled Optomechanical SystemIOSRJAP
Using short-time dynamics and analytical solution of Heisenberg equation of motion for the Hamiltonian of quadratically-coupled optomechanical system for different field modes, we have investigated the existence of higher-order single mode squeezing, sum squeezing and difference squeezing in absence of driving and dissipation. Depth of squeezing increases with order number for higher-order single mode squeezing. Squeezing factor exhibits a series of revival-collapse phenomena for single mode, which becomes more pronounced as order number increases. In case of sum squeezing amounts of squeezing is greater than single mode higher-order squeezing (n = 2). It is also greater than from difference squeezing for same set of interaction parameters. Sum squeezing is prominently better for extracting information regarding squeezing.
Control of vibration through an innovative isolation technique of a multistor...eSAT Journals
Abstract
The paper presents a simple and an innovative idea regarding vibration isolation technique of a multistory building using magnetic
field and is proposed to application in the field of civil engineering structures. This idea is fully based on hypothetical concept, but the
objective is to explore this idea or concept in to the entire community which may be a potential sector for the effective vibration
isolation system. The technique is described based on the magnetic properties of materials and a magnetic field characteristic which
depends on the amount of current flow, number of turns in coil, distance between electromagnet and the magnetic materials.
Therefore using magnetic field, the attraction induced between magnet and magnetic materials, a force could finally be developed on
the floor of building. This force would become effective until and unless the power is cutoff. Therefore this induced force is actually
acts as a live load on the structure which indirectly increases the weight and this has been described in this paper.
Keywords: - Isolation, vibration, frequency, magnetic field, performance based design, damping
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Supersymmetric U(1)_{B-L} x U(1)_R model with dark matter, muon g-2 and Z' ma...Özer Özdal
We study the low scale predictions of supersymmetric standard model extended by $U(1)_{B-L}\times U(1)_{R}$ symmetry, obtained from $SO(10)$ breaking via a left-right supersymmetric model, imposing universal boundary conditions. Two singlet Higgs fields are responsible for the radiative $U(1)_{B-L}\times U(1)_{R}$ symmetry breaking, and a singlet fermion $S$ is introduced to generate neutrino masses through inverse seesaw mechanism. The lightest neutralino or sneutrino emerge as dark matter candidates, with different low scale implications. We find that the composition of the neutralino LSP changes considerably depending on the neutralino LSP mass, from roughly half $U(1)_R$ bino, half MSSM bino, to singlet higgsino, or completely dominated by MSSM higgsino. The sneutrino LSP is statistically much less likely, and when it occurs it is a 50-50 mixture of right-handed sneutrino and the scalar $\tilde S$. Most of the solutions consistent with the relic density constraint
survive the XENON 1T exclusion curve for both LSP cases. We compare the two scenarios and investigate parameter space points and find consistency with the muon anomalous magnetic moment only at the edge of $2\sigma$ deviation from the measured value. However, we find that the sneutrino LSP solutions could be ruled out completely by strict reinforcement of the recent $Z^\prime $ mass bounds. We finally discuss collider prospects for testing the model.
MAGNETOSTATIC SURFACE WAVES IN A LEFT HANDED / FERRITE/ METAL-STRIP-GRATING S...ijrap
The dispersion characteristics for magnetostatic surface waves in a left handed ( LHM)/ferrite/ metal-stripgrating
structure have been investigated. We found that, the waveguide supports backward TE waves
since both permittivity and magnetic permeability of LHM are negative. We also illustrated the
dependence of wave frequency on the reduced wave number for a grating shielding parameter, g values
restricted by the range 0 ≤ g ≥ 1. It is shown that the grating shielding parameter, g induces
magnetostatic backward shorter waves . The leakage through the grating increases with the wave number. The shorter backward magnetostatic waves are guided by the thicker waveguide where the best confinement is achieved
Modeling of the damped oscillations of the viscous beams structures with swiv...eSAT Journals
Abstract
Mechanic studies realized on the two dimensional beams structures with swivel joints show that in statics, the vertical displacement is
continuous, but the rotation is discontinuous at the node where there is a swivel joint. Moreover, in dynamics, many authors do not
usually take into account the friction effect, modeling of these structures. We propose in this paper, a modeling of the beams structures
with swivel joints which integrates viscosity effects in dynamics. Hence this work we will present the formulation of motion equations
of such structures and the modal analysis method which is used to solve these equations.
Keywords: Beams, Swivel joint, Viscosity, Vibration, Modal Method.
Simulation of a fatigue crack problem in electronic devicesCADFEM Austria GmbH
Fatigue crack growth under active cycling conditions is simulated using the cohesive zone modeling concept within the framework of the Finite Element Method.
To this end, a cyclic cohesive zone model based on a damage evolution equation is extended onto the case of transient thermal loading conditions and is implemented into ANSYS. The thermal and mechanical interaction of the cohesive surfaces is taken into account for both open and closed crack states. By incorporating the temperature dependence of the cohesive zone model parameters, the model is also extended onto cases of nonisothermal fatigue.
To speed-up fatigue simulations, the cyclic cohesive zone model is equipped with the cycle jump technique based on direct iteration of the damage evolution equation.
The implemented thermomechanical cyclic cohesive zone model is applied to a problem of interfacial debonding between two layers of a power metallization stack subjected to the active thermal cycling.
Supersymmetric U(1)_{B-L} x U(1)_R model with dark matter, muon g-2 and Z' ma...Özer Özdal
We study the low scale predictions of supersymmetric standard model extended by $U(1)_{B-L}\times U(1)_{R}$ symmetry, obtained from $SO(10)$ breaking via a left-right supersymmetric model, imposing universal boundary conditions. Two singlet Higgs fields are responsible for the radiative $U(1)_{B-L}\times U(1)_{R}$ symmetry breaking, and a singlet fermion $S$ is introduced to generate neutrino masses through inverse seesaw mechanism. The lightest neutralino or sneutrino emerge as dark matter candidates, with different low scale implications. We find that the composition of the neutralino LSP changes considerably depending on the neutralino LSP mass, from roughly half $U(1)_R$ bino, half MSSM bino, to singlet higgsino, or completely dominated by MSSM higgsino. The sneutrino LSP is statistically much less likely, and when it occurs it is a 50-50 mixture of right-handed sneutrino and the scalar $\tilde S$. Most of the solutions consistent with the relic density constraint
survive the XENON 1T exclusion curve for both LSP cases. We compare the two scenarios and investigate parameter space points and find consistency with the muon anomalous magnetic moment only at the edge of $2\sigma$ deviation from the measured value. However, we find that the sneutrino LSP solutions could be ruled out completely by strict reinforcement of the recent $Z^\prime $ mass bounds. We finally discuss collider prospects for testing the model.
MAGNETOSTATIC SURFACE WAVES IN A LEFT HANDED / FERRITE/ METAL-STRIP-GRATING S...ijrap
The dispersion characteristics for magnetostatic surface waves in a left handed ( LHM)/ferrite/ metal-stripgrating
structure have been investigated. We found that, the waveguide supports backward TE waves
since both permittivity and magnetic permeability of LHM are negative. We also illustrated the
dependence of wave frequency on the reduced wave number for a grating shielding parameter, g values
restricted by the range 0 ≤ g ≥ 1. It is shown that the grating shielding parameter, g induces
magnetostatic backward shorter waves . The leakage through the grating increases with the wave number. The shorter backward magnetostatic waves are guided by the thicker waveguide where the best confinement is achieved
Modeling of the damped oscillations of the viscous beams structures with swiv...eSAT Journals
Abstract
Mechanic studies realized on the two dimensional beams structures with swivel joints show that in statics, the vertical displacement is
continuous, but the rotation is discontinuous at the node where there is a swivel joint. Moreover, in dynamics, many authors do not
usually take into account the friction effect, modeling of these structures. We propose in this paper, a modeling of the beams structures
with swivel joints which integrates viscosity effects in dynamics. Hence this work we will present the formulation of motion equations
of such structures and the modal analysis method which is used to solve these equations.
Keywords: Beams, Swivel joint, Viscosity, Vibration, Modal Method.
Simulation of a fatigue crack problem in electronic devicesCADFEM Austria GmbH
Fatigue crack growth under active cycling conditions is simulated using the cohesive zone modeling concept within the framework of the Finite Element Method.
To this end, a cyclic cohesive zone model based on a damage evolution equation is extended onto the case of transient thermal loading conditions and is implemented into ANSYS. The thermal and mechanical interaction of the cohesive surfaces is taken into account for both open and closed crack states. By incorporating the temperature dependence of the cohesive zone model parameters, the model is also extended onto cases of nonisothermal fatigue.
To speed-up fatigue simulations, the cyclic cohesive zone model is equipped with the cycle jump technique based on direct iteration of the damage evolution equation.
The implemented thermomechanical cyclic cohesive zone model is applied to a problem of interfacial debonding between two layers of a power metallization stack subjected to the active thermal cycling.
This paper present design of new type of electromagnetic damper or eddy current damper
which has advantages of no mechanical contact, higher reliability and stability, high efficiency and
compactness. By using this damper we can minimized damping of different masses and thereby damping
coefficient. The damper is composed of neodymium iron boron grade N 50 magnet .By using this damper I
found greater difference in damping when experimental result are compared with analytical result.
High Performance Germanium Double Gate N-MOSFETIJMER
The current MOSFET technology supports scaling down to nanometer. To achieve
enhanced transistor switching, it is difficult to keep the equivalent driver current at the same level
since it changes by the certain restrictions like effective masses, density of states, uniaxial- and
biaxial- strain; band structure, channel orientation, channel mobility, off-state leakage, switching
delay in nano-scale and parasitic latch up. Current strained-Si is the ruling technology for
intensifying the performance of MOSFET and development of strain can provide a better solution to
the scaling. The future of nano-scale MOSFETs relies on exploration of novel higher mobility channel
materials such as stained-Ge and strained III-V groups that might perform even better than very
highly strained-Si. In addition, parameters such as injection velocity, short channel length effect and
Band-to-Band Tunneling (BTBT) result in reduction of inversion charge, increase in leakage current,
resulting in decrease in the drive current. While developing accurate model of MOSFETs all these
complex effects should be captured. It is proposed to
1. Design high performance double gate n-MOSFET with channel material Ge.
2. Benchmarked & stimulate high performance double gate n-MOSFET by using the simulation
techniques.
State-Switched Control Algorithm for Multi Degree of Freedom Smart Base Isola...Sajjad Ahmad
International Conference on Earthquake Engineering and Seismology (ICEES 2011), NUST, Islamabad, Pakistan April 25-26, 2011
by
Muhammad Usman, Sajjad Ahmad, Hyung-Jo Jung
Magnetic Flux Controllers in Induction Heating and Melting by Robert Goldstei...Fluxtrol Inc.
MAGNETIC FLUX CONTROLLERS are
materials other than the copper coil that are used
in induction systems to alter the flow of the magnetic
field. Magnetic flux controllers used in
power supplying components are not considered
in this article.
Magnetic flux controllers have been in existence
since the development of the induction
technique. Michael Faraday used two coils of
wire wrapped around an iron core in his experiments
that led to Faraday’s lawof electromagnetic
induction, which states that the electromotive
force (emf) induced in a circuit is directly proportional
to the time rate of change of the magnetic
flux through the circuit. After the development
of the induction principle, magnetic flux controllers,
in the form of stacks of laminated steel, found
widespread use in the development of transformers
for more efficient transmission of energy
(Ref 1, 2).
Magnetic cores gained widespread use in the
transformer industry because they increased
the amount of magnetic flux produced with
the same alternating current. The higher the
magnetic flux, the higher the emf, which results
in an increase in energy transfer efficiency from
the primary winding to the secondary winding.
Similar to transformers, magnetic cores were
used on early furnaces for induction melting
(Ref 1, 2). The benefits of magnetic flux controllers
vary depending on the application. For
induction heating, magnetic flux controllers can
provide favorable and unfavorable paths for magnetic
flux to flow, resulting in increased heating in
desired areas and reduced the heating in undesirable
areas, respectively.Magnetic flux controllers
are not used in every induction heating application,
but their use has increased (Ref 3, 4).
Copyright 2014, ASM International, www.asminternational.org. This article was published in ASM Handbook, Volume 4C: Induction Heating and Heat Treatment and is made available as an electronic reprint with the permission of ASM International. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplications of any material in this article for a fee or for commercial purposes, or modification of the content of this article is prohibited.
Characterization of Quasi-Keplerian, Differentially Rotating, Free-Boundary L...Sérgio Sacani
We present results from pulsed-power driven differentially rotating plasma experiments designed to
simulate physics relevant to astrophysical disks and jets. In these experiments, angular momentum is injected
by the ram pressure of the ablation flows from a wire array Z pinch. In contrast to previous liquid metal and
plasma experiments, rotation is not driven by boundary forces. Axial pressure gradients launch a rotating
plasma jet upward, which is confined by a combination of ram, thermal, and magnetic pressure of a
surrounding plasma halo. The jet has subsonic rotation, with a maximum rotation velocity 23 3 km=s. The
rotational velocity profile is quasi-Keplerian with a positive Rayleigh discriminant κ2 ∝ r−2.80.8 rad2=s2.
The plasma completes 0.5–2 full rotations in the experimental time frame (∼150 ns).
Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
The Art Pastor's Guide to Sabbath | Steve ThomasonSteve Thomason
What is the purpose of the Sabbath Law in the Torah. It is interesting to compare how the context of the law shifts from Exodus to Deuteronomy. Who gets to rest, and why?
Welcome to TechSoup New Member Orientation and Q&A (May 2024).pdfTechSoup
In this webinar you will learn how your organization can access TechSoup's wide variety of product discount and donation programs. From hardware to software, we'll give you a tour of the tools available to help your nonprofit with productivity, collaboration, financial management, donor tracking, security, and more.
The Indian economy is classified into different sectors to simplify the analysis and understanding of economic activities. For Class 10, it's essential to grasp the sectors of the Indian economy, understand their characteristics, and recognize their importance. This guide will provide detailed notes on the Sectors of the Indian Economy Class 10, using specific long-tail keywords to enhance comprehension.
For more information, visit-www.vavaclasses.com
Synthetic Fiber Construction in lab .pptxPavel ( NSTU)
Synthetic fiber production is a fascinating and complex field that blends chemistry, engineering, and environmental science. By understanding these aspects, students can gain a comprehensive view of synthetic fiber production, its impact on society and the environment, and the potential for future innovations. Synthetic fibers play a crucial role in modern society, impacting various aspects of daily life, industry, and the environment. ynthetic fibers are integral to modern life, offering a range of benefits from cost-effectiveness and versatility to innovative applications and performance characteristics. While they pose environmental challenges, ongoing research and development aim to create more sustainable and eco-friendly alternatives. Understanding the importance of synthetic fibers helps in appreciating their role in the economy, industry, and daily life, while also emphasizing the need for sustainable practices and innovation.
How to Create Map Views in the Odoo 17 ERPCeline George
The map views are useful for providing a geographical representation of data. They allow users to visualize and analyze the data in a more intuitive manner.
How to Split Bills in the Odoo 17 POS ModuleCeline George
Bills have a main role in point of sale procedure. It will help to track sales, handling payments and giving receipts to customers. Bill splitting also has an important role in POS. For example, If some friends come together for dinner and if they want to divide the bill then it is possible by POS bill splitting. This slide will show how to split bills in odoo 17 POS.
2. 1516 IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY, VOL. 21, NO. 3, JUNE 2011
Fig. 2. Schematic diagram of experimental setup in static measurement.
Fig. 4. Schematic diagram of experimental setup in a damped oscillation anal-
ysis and a damped harmonic oscillator model.
Fig. 3. Magnetic force vs. gap in superconductivity (SC) state and normal con-
ductivity (NC) state. Fig. 5. Damped oscillation of the levitation part suspended by HTS.
fluxes are pinned in the HTS, a 0.45%C steel rod (8 mm in di- where and are the natural an-
ameter and 50 mm in thickness) is quasi-statically approached gular frequency and damping ratio, respectively. Here, indi-
the bottom of cryostat ranging from 3 mm to 0 mm at 0.1 mm/s. cates the displacement from the equilibrium point of the oscil-
During the experiment, the magnetic force and the gap are mea- lation system. Therefore, the stiffness and damping constants
sured by means of a load cell (LC1205-K020, A&D) and a laser can be calculated by modulating measured oscillation by (2).
displacement sensor (LC2440, KEYENCE), respectively. The A schematic of experimental setup in the damped oscillation
measurement is conducted in not only superconductivity (SC) analysis is shown in Fig. 4. As the procedure, first, a stable lev-
state but also normal conductivity (NC) state for comparison. itation of a steel rod is realized by the properties obtained in
The relationships between the magnetic force and the gap in Section III. According to the results, the mass of the levitation
both the states are shown in Fig. 3. It should be noted that unlike part (including the steel rod) is adjusted so as to shift the equi-
in the NC state, the magnetic force decreases below a certain gap librium point between the gravity and the magnetic force to be
and becomes to have positive stiffness in the SC state—the max- within the region of positive stiffness (Fig. 3). In this condition,
imum attractive force 2.57 N at 1.45 mm. The magnetic force an external impulse force is given to generate damped oscilla-
shows a hysteresis in the approaching and retreating processes. tion in z-direction. The position of levitation part
It might be explained that some fluxes pinned in the HTS are is measured by the laser displacement sensor with the sampling
released from the pinning center resulting in being trapped in frequency of 100 Hz. A representative result of attenuation be-
other pinning center [2], [7]. havior is shown in Fig. 5. The result shows that the natural fre-
quency increases with time transition. It is considered that the
IV. DYNAMIC MEASUREMENT stiffness increases with decrease in the gap within the region
of positive stiffness, as shown in Fig. 3. The relationships be-
A. Damped Oscillation Analysis tween the initial position where the attenuation starts and the
Dynamic properties in the levitation system are discussed by spring and damping constants are shown in Figs. 6 and 7, re-
using a damped oscillation analysis. Dynamic properties can spectively. The graphs show that in the measurement range the
be generally calculated by the attenuation of oscillation. In a spring constant decreases with increase in initial position. Also,
damped harmonic oscillator model as shown in Fig. 4, the mo- the value agrees well with the slope of line at 0.7 mm in the
tion equation of the mass is described as: static measurement (Fig. 3). On the contrary, the damping con-
stant increases with increase in initial position. This implies that
(1) increase of hysteresis affects the attenuation of levitation system
where and are the spring and damping constants, respec- (later we will discuss). Here, it can be said that dynamic proper-
tively. The solution of (1) is given as follow: ties of our system are related to the amplitude of the oscillation.
The damped oscillation analysis, however, can reveal only the
(2) properties depending on the natural frequency on the specific
3. SAKAI AND HIGUCHI: PROPERTIES OF MAGNETIC LEVITATION SYSTEM USING HIGH-TEMP SUPERCONDUCTOR 1517
Fig. 6. Spring constant vs. initial position in damped oscillation analysis.
Fig. 8. Schematic diagram of experimental setup in measurement using repet-
itive control.
Fig. 7. Damping constant vs. initial position in damped oscillation analysis.
Fig. 9. Spring constant vs. input frequency in measurement using repetitive
control.
levitation point. In next section, a new measurement method is
introduced to evaluate the dynamic properties as a function of
the velocity.
B. Viscoelastic Measurement Using Repetitive Control
To further investigate dynamic properties of the system, a
novel measurement method using repetitive control is proposed.
In this method, repetitive control, which is effective for a peri-
odic servo system, is implemented because it is useful to ad-
just an output to track a periodic target, modifying the input
for the next cycle based on the tracking error [10]. A voice coil
motor (VCM) was employed as an actuator to generate the os-
cillation. Because of the repeatability and robustness, the differ-
ence between the current through the HTS under the loaded and Fig. 10. Damping constant vs. input frequency in measurement using repetitive
no-loaded conditions represents the net current to move against control.
the load. When giving the sinusoidal motion by repetitive con-
trol, the sine and cosine components of the current represent
the elasticity and viscosity, respectively. It should be noted that the input current is consistently controlled by a PC, based on
repetitive control using the VCM [11] is, therefore, useful to tracking error. The sinusoidal input is given until 60 cycles, but
evaluate the dynamic properties of the levitation system, be- repetitive control is applied every 3 cycles; each cycle has 1000
cause the input oscillation frequency can be flexibly changed samplings. The measurement is conducted in not only the SC
with excellent repeatability. A schematic of the experimental state but also the NC state for comparison. The relationships
setup is shown in Fig. 8 and the detail of experimental proce- between spring and damping constants and the input frequency
dure is as follows. In this experiment, the same procedure is for the oscillation are shown in Figs. 9 and 10, respectively. The
used as that in the above-mentioned experiments; only the dif- spring constant has the positive stiffness in the SC state and neg-
ference point is that a VCM (X-1741, NEOMAX), on which ative in the NC state. The absolute value decreases as increase
the steel rod is attached, to move the rod instead of manual of input frequency. Meanwhile the damping constant decreases
movement. A sinusoidal position oscillation with the amplitude as increase of input frequency and varies more notably than the
of 0.2 mm is input at the reference point—0.5 or 1.0 mm far spring constant. This is because the cosine wave component in
from the bottom of the cryostat. The position of the rod is mea- the obtained current is significantly smaller than the sine wave
sured by a linear encoder (Mercury2000, MicroE Systems), and component and the accidental error cannot be ignored.
4. 1518 IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY, VOL. 21, NO. 3, JUNE 2011
static measurement and the value is larger when the reference
point is closer to the bottom of the cryostat in both measure-
ments. Therefore, in our levitation system, the hysteresis loss
significantly affects the attenuation of oscillation.
VI. CONCLUSION
This work discussed the dynamic properties of the system
in which a soft magnetic material can be levitated by an
HTS. To achieve this, the static and dynamic properties were
investigated, modulating the system by a damped harmonic
oscillator model. The measurements were performed in two
Fig. 11. Magnetic force vs. gap in a cycle of the amplitude of 0.2 mm at 0.5 ways. In damped oscillation analysis, spring constant decreased
mm and 1.0 mm. as increase of initial position of the attenuation and agrees
with the results in static measurement. On the contrary, the
damping constant increased as increase of initial position. To
evaluate the dynamic properties as a function of the oscillating
velocity, a novel measurement method using repetitive control
was proposed. The results showed that both of the spring and
damping constants decreased as increase of the input oscilla-
tion frequency. And evaluation of hysteresis losses in both the
measurements implied that hysteresis significantly affects the
attenuation of oscillation.
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magnetic hysteresis, friction, air resistance, etc. In this work, [5] M. Ghodsi, T. Ueno, and T. Higuchi, “Improvement of magnetic cir-
the hysteresis mentioned in Section III is specially focused on cuit in levitation system using HTS and soft magnetic material,” IEEE
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and compared in both the static and dynamic measurements. In [6] M. Ghodsi, T. Ueno, and T. Higuchi, “The characteristics of trapped
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[10] T. Higuchi and T. Yamaguchi, “Cutting tool positioning by periodic
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Therefore, the hysteresis losses in the static and dynamic mea- [11] T. Nonomura, W. Rhie, and T. Higuchi, “Load estimation of voice coil
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Conference, 2009, vol. 1, pp. 957–958.
measurements are plotted in Fig. 12. It should be noted that hys- [12] G. Sandberg and R. Ohayon, Computational Aspects of Structural
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